* Nadal says injury problem started in February
* Doctor says he is suffering from Hoffa's syndrome
(Updates with quotes from federation doctor)
MANACOR, Spain, Aug 17 (Reuters) - Rafa Nadal said he must
fully recover from a nagging knee problem known as Hoffa's
syndrome before returning to competition and was a doubt for
next month's Davis Cup semi-final against the United States.
Spain's world number three has not played since suffering a
shock second-round Wimbledon defeat by lowly ranked Czech Lukas
Rosol in June. He missed the Olympic Games and on Wednesday he
withdrew from the U.S. Open.
"The important thing is to recover well and come back when
my knee is a hundred percent perfect," Nadal told Reuters
television in an interview in his hometown of Manacor in
Mallorca.
"We'll see if I will be ready for Gijon, for the Davis Cup.
My goal, my dream is to be there if the captain has confidence
in me, but it always depends on the captain and the knee."
Due to his aggressive style of play, Nadal has suffered a
string of physical problems during his career, including a foot
injury in 2005 and more recently with his knees.
He pulled out of the 2008 Tennis Masters Cup with
tendinitis, and a year later the same complaint led to him
missing the chance to defend his title at Wimbledon.
A knee injury forced him to withdraw from the Australian
Open in 2010 and in March of this year he had to pull out of a
semi-final clash with Andy Murray at the Sony Ericsson Open in
Miami due to a knee problem.
DIFFERENT INJURY
"The injury is not the same (as before)," he said.
"It is an injury that started around February before Indian
Wells. I played these months with some problems, like in Miami,
but normally I had the control of the pain, of the injury.
"But after (winning the French Open at) Roland Garros the
injury got worse and it was impossible to continue competing
and, of course, the important thing today is to recover as fast
as possible after not arriving in perfect condition at
Wimbledon."
Spanish tennis federation (RFET) doctor Angel Ruiz Cotorro
said Nadal was suffering from a problem known as Hoffa's
syndrome which is a swelling round the tendon just below the
kneecap in his left leg.
"It is uncomfortable and painful, but it is not serious,"
Cotorro was quoted as saying on the Marca website.
"He is recovering well. Next week they will do tests and if
the result is positive we will continue with the same
treatment."
Nadal added: "I am practising hard on the recovery with the
physio in the gym, to not lose my fitness, I am a few days
outside of the tennis court to try and recover faster."
Davis Cup holders Spain beat Austria 4-1 in April, without
Nadal, to set up a semi with the U.S. on Sept. 14-16.
(Reporting by Carlos Herrera, writing by Mark Elkington in
Madrid, editing by Ken Ferris)